add specific CONTRIBUTING.md file

CONTRIBUTING.md

+## Contributing to GitLab Development Kit
+
+The source of GitLab Development Kit is [hosted on
+GitLab.com](https://gitlab.com/gitlab-org/gitlab-development-kit/) and
+contributions are welcome!
+
+## Contributor license agreement
+
+By submitting code as an individual you agree to the
+[individual contributor license agreement](https://gitlab.com/gitlab-org/gitlab-ce/doc/legal/individual_contributor_license_agreement.md).
+By submitting code as an entity you agree to the
+[corporate contributor license agreement](https://gitlab.com/gitlab-org/gitlab-ce/doc/legal/corporate_contributor_license_agreement.md).

README.md

@@ -17,11 +17,7 @@ different components, and start/stop them when you work on GitLab.
 ## Contributing to GitLab Development Kit
-The source of GitLab Development Kit is [hosted on
-GitLab.com](https://gitlab.com/gitlab-org/gitlab-development-kit/) and
-contributions are welcome, per the [contribution
-guidelines](https://gitlab.com/gitlab-org/gitlab-ce/CONTRIBUTING.md) and
-the contributor license agreements linked to from there.
+Contributions are welcome, see [`CONTRIBUTING.md`](CONTRIBUTING.md) for more details.
 ## Getting started